This invention generally relates to fasteners, and more specifically to snap fasteners or clasps adapted to releasably join two associated parts to each other.
Various snap fasteners are known in the prior art. Such fasteners take various shapes and forms, and each different fastener is generally particularly suitable for particular applications. One of the most common types of fasteners is the snap or button-type fasteners such as the type disclosed in U.S. Pat. No. 1,904,122, which is a fastener adapted to be used on garments or articles intended to be laundered. In this patent, a stud is permanently attached to one part of a garment and a ring eyelet or grommet is permanently attached to another part of the garment. Another member is inserted into the grommet in the manner of a stud, and when there assembled it serves as a socket to detachably receive the stud and hold the separate parts of the garment together. This and numerous other similar fasteners are in common use. However, such fasteners are generally small in size and do not provide suitable gripping means, the portions of the fastener bearing the stud and socket being attached directly to the fabric or material comprising the garment. Accordingly, while it is relatively simple to join the separate parts of the fastener, separation thereof requires gripping the garment fabric and application of sometimes extensive stresses to the fabric to effectuate separation. Such extensive stresses may in time tear portions of the garment to which the fasteners are attached.
Another form of fastener or clasp is described in U.S. Pat. No. 2,765,471 which is adapted to be used with a brassiere of the type which opens in the front and is provided with breast-supporting cups. The cups are normally linked together with the clasp. The clasp includes a female member having a socket portion into which a head of a male member is receivable. However, to join the male and female members, the head must be inserted into the fenestration while rotated out of the plane of the female member. After the head has been inserted through the fenestration, it is rotated back into the plane of the female member and the head is socketed within the fenestration by means of suitable shoulders. While such a clasp is useful for brassieres which open in the front and the like, it is in some instances inconvenient to use, particularly when the fastener is used in the back of the wearer or in some other location which is difficult or inconvenient to reach.
Partially to overcome the above problems, there has been devised separable fasteners, of the type generally disclosed in U.S. Pat. Nos. 3,200,464 and 3,798,711 which include male and female connector portions which are joined by slidingly inserting the male member through a fenestration in the female member, while these members are maintained substantially in a common plane throughout the joining operation. Such fasteners are universally applicable, and may be used to join adjacent areas or edges of an item of clothing, jewelry, drapery or equipment requiring the joining of separable parts or edges. This type of fastener includes a resilient tongue or latch member which is formed on the male member for deflection during insertion into the female member, and subsequent snapping back to the original position once disposed within the female member. Suitable shoulders or abutting surfaces then maintain the male and female members locked to each other until such time that the resilient tongue member is manually depressed to release or separate the abutting surfaces. While the separable fasteners of the type just described serve well in most applications, they have the drawback that there is a movable or deflectable member which may, for various reasons, cease to function properly or actually break off from the male member. In either case, the fastener members may be subject to inadvertent separation. Additionally, where the resilient tongue member protrudes or is beyond the confines of the female member during engagement therewith, it may inadvertently be depressed to cause undesirable separation of the members from each other. Excessive longitudinal forces on the male and female members tending to separate the same may also be sufficient to deflect the resilient tongue member and thereby disengage the abutting or engaging locking surfaces. Since the operation of the fastener is dependent upon the resilient tongue member, a separable fastener tends to be, under certain circumstances, positionally unstable and may cause separation of the parts or items which have been fastened together to the inconvenience and discomfort of the user. Such positional instability limits, to some extent, the longitudinal or pulling forces which can be applied in opposite directions on the male and female members.